It was a curiously anonymous setting for such a dramatic confrontation. Think of London’s Royal Courts of Justice, and images of ancient oak-panelled chambers immediately swim into view. But Courtroom 73, where Deborah Lipstadt went to war five years ago against the champion of Holocaust denial, David Irving, could easily have been some anonymous seminar room on a 1970s campus.

The furnishings were drab and functional, adorned with rows of files and laptop computers. After spending one afternoon there during the three-month libel, I wondered how anyone could possibly stay sane in such a depressing room over such a long period.

The answer, of course, is that amidst the swirl of minutiae and legalese, the case generated riveting theater. Everyone present in the room — from reporters to concentration camp survivors — was aware that the outcome would had historic consequences.

The title of Ms. Lipstadt’s memoir is no overstatement. By demolishing Mr. Irving’s claims, her team of lawyers stripped Holocaust denial of the few lingering shreds of credibility it had ever possessed. That may sound a straightforward task; Holocaust deniers are, after all, the flat-earthers of our age. But it is worth remembering that until he met defeat in this case — which he himself initiated — David Irving was widely regarded as a legitimate if cranky historian of the Third Reich.

The real mystery is how on earth he ever thought he would prevail. Having issued a libel writ against Ms. Lipstadt in 1995 over her book, “Denying The Holocaust,” the British author had ample time for second thoughts. Anthony Julius, the astute London solicitor who marshalled Ms. Lipstadt’s team of researchers and historians, assumed that Mr. Irving was simply seeking publicity and would abandon the suit sooner or later.

If Mr. Irving made his task even more difficult by representing himself in court, the incriminating evidence scattered throughout his journals and archives gave his opponents no end of ammunition. The historian John Lukacs — quoting his Spanish counterpart, Altamira — has spoken of Mr. Irving’s “idolatory of the document,” that is, a willingness to build a towering edifice on a single document or fragment.

As Mr. Julius and Ms. Lipstadt’s barrister, QC Richard Rampton, demonstrated over and again, the plaintiff was so eager to minimize or conceal the Nazis’ crimes that he not only made a point of quoting documents out of context but mistranslated them into the bargain. To see him caught red-handed again and again is almost the stuff of farce. Even Ms. Lipstadt had to repress laughter at times.

There was one all-important factor working in her antagonist’s favor, however. In Britain, in stark contrast to America’s libel laws, the burden of proof rests on the defendant. (British publishers are acutely aware of this problem, which also explains why so many foreign VIPs choose to pursue cases in London rather than the country where the offending material was actually published.)

Ms. Lipstadt, a professor at Emory University, was thus put on the back foot. What made her position even more frustrating was that Mr. Irving, a past master of public relations, often managed to present himself in media reports as the victim of a legal juggernaut which he had, in fact, set it in motion.

The story of the confrontation has been told before, most notably in D. D. Guttenplan’s book “The Holocaust on Trial” and “Telling Lies About Hitler” written by the defence’s chief witness, the Cambridge historian Richard Evans. Still, Ms. Lipstadt’s acount of her journey from uncertainty and despair to triumph is immensely readable.

At her lawyers’ request, she did not testify during the trial itself, and kept her public statements to a minimum. Finally free to unburden herself, she has delivered an account that is fast-moving, shrewd and often unexpectedly droll. Unfamiliar with the archaic rituals of the British legal system, she initially found herself chafing against the coolly forensic approach of her barrister, Mr. Rampton. (Mr. Julius, as a solicitor, was not allowed to address the court.) It is only as the case gains momentum that she realizes that Mr. Rampton’s emotional commitment to the trial is no smaller than hers.

We gain a vivid sense of Ms. Lipstadt’s combative personality in the chapters devoted to her liberal New York upbringing and her youthful visits to Israel. (Unlike many of her contemporaries, she did not wait until the Six Day War to discover her emotional bond with the Jewish state.)

Mr. Irving’s assault on her integrity was consequently more than a purely scholarly affair. Ms. Lipstadt was so consumed by the case and its ramifications that, while in London, she was slow to notice the incongruity of her choice of leisure outing. In the circumstances, “The Merchant of Venice” and a camp “singalong” version of “The Sound of Music”, tuneful Nazis and all, were hardly the ideal way to relax.

Even in the moment of victory, a sour note intruded. Immediately after the verdict — which was even more conclusive than she could have hoped — two distinguished British historians, Sir John Keegan and Donald Cameron Watt, who had both been subpoenaed to give evidence by Irving — published newspaper articles which appeared to make excuses for their countryman.

Mr. Watt asked plaintively, “Show me one historian who has not broken into a cold sweat at the thought of undergoing similar treatment?” It was a strange complaint, given what we now know about Mr. Irving’s modus operandi.

Sir John’s comments were even odder. Praising Mr. Irving’s “strong, handsome” appearance, he seemed to find him much more worthy of sympathy than the defendant. He continued: “Professor Lipstadt, by contrast, seems as dull as only the self-righteously politically correct can be. Few other historians had ever heard of her before this case. Most will not want to hear from her again. Mr. Irving, if he will only learn from this case, still has much that is interesting to tell us.” Reviewing this book in The Washington Post, the controversial Daniel Jonah Goldhagen argued that Mr. Irving’s apologetics had found favor among “a part of the politicized historical profession that has a weakness for such exculpatory writings.”

That seems a slight exaggeration. As Ms. Lipstadt acknowledges, even the judge’s verdict praised Mr. Irving’s work as a military historian. But it remains puzzling that two such distinguished figures — who had both dismissed Mr. Irving’s Holocaust theories — were still willing to go out of their way to find virtue in a writer who displayed so little respect for truth.

Ms. Lipstadt suspects the Old Boy network may be to blame. It is a depressing thought. Thankfully, the rest of “History on Trial” restores one’s faith in the power of good scholarship.

Clive Davis writes for The Times of London and keeps a weblog at clivedavis.blogspot.com